Strongback for pressure vessel



Aug. 22, 1961 G. E. FLURSCHUTZ ETAL STRONGBACK FOR PRESSURE VESSEL FiledApril 18, 1958 United States atent 2,997,279 SI RONGBACK FOR PRESSUREVESSEL Glenn E. Flurschutz and J Bernard Cott, Wellsville, N.Y.,a'ssignors to The Air Preheater Corporation, New York, N.Y., acorporation of New York Filed Apr. 18, 1958, Ser. No. 729,360 7 Claims.(Cl. 257-445) The present invention relates generally to theconstruction of vessels that are to be subjected to high internalpressures, and more specifically it refers to the construction of platetype heat exchange apparatus adapted for use with high pressure fluids.

In a rectangular pressure vessel the walls thereof are usually of theribbed plate strongback variety in which a housing having plate walls ismerely reinforced at selected intervals by stiflening ribs to impart thenecessary strength thereto. Such a strongback can readily be designed towithstand any predetermined pressure, however when the temperature ofthe pressurized fluid is other than ambient there will exist atemperature gradient through the strongback with its attendant thermaldistortion. In such pressure vessels operated at high temperatures,internal ligaments or plates may be connected to opposing walls toprovide rigidity, however the temperature diflerence between theseinternal ligaments and the extremities of the strongback elfects highstresses within the core of the heat exchanger, the strongback, and itsrelated connections.

The proposed strongback eliminates this basic problem since it is freeto move as the core expands and contracts. As a result of this inherentflexibility, no great stresses are created in the structure and thestrongback effectively carries out its primary function of safelycontaining the internal pressure forces.

The invention will be better understood upon reference to theaccompanying drawing in which:

FIGURE 1 represents a perspective view of a plate type heat exchangerhaving a strongback constructed according to this invention.

FIGURE 2 illustrates a modified form of strongback arrangement.

In FIGURE 1 is shown a plate type heat exchanger for the transfer ofheat between hot gas at low pressure and cooler air that exists atrelatively high pressure. The heat exchanger includes essentially aseries of envelopes comprising a pair of plates 14 spaced apart by aseries of parallel tubes 16 to provide a fluid passageway therebetweenwith the sides of the tubes providing a series of transverse finsextending across the passageway between plates 14. The envelopes thusformed are closed at their lateral edges by closure bars 18 that areusually welded between the plates to provide an integral assembly duringconstruction. A plurality of such envelope components are assembled inalignment with closure bars 20 at opposite ends thereof adapted to spacethe envelope units apart to provide passageways for the flow of a secondfluid therebetween.

A series of such envelope units thus provide a core through which fluidsmay flow with the express object of transferring heat from one fluid toanother. To further contain the different fluids in the passagewaysbetween the walls of such a heat exchange apparatus a housing isconstructed around the assembly. Such a housing normally includes a pairof side plates 22 having an inlet aperture 24 and an outlet aperture 26at opposite ends thereof adapted to direct the flow of air to and fromthe passageways 28 formed between envelopes. At opposite ends of theassembly end plates 32 are welded between the side plates 22 to completethe housing structure encircling the assembled envelopes and providingouter walls for air passageways 34 at opposite ends of the structure.

Patented Aug. 22, 1961 The fluid pressure in interior pasageways 28 iscompletely neutralized in such a structure by equal pressures in similarpassageways on opposite sides of the envelopes, however the high fluidpressure in passageways 34 acts upon the entire area of plates 32 withno neutralizing pressure on the opposite side thereof so as to requirethat plate 32 itself be given suflicient strength to withstand the fluidpressures in the passageway enclosed.

In accordance with this invention a strongback assembly is provided atopposite ends of the assembled apparatus to insure adequate structuralrigidity for the outer walls 32 of passageways 34. The strongbackassembly comprises a pair of heavy plate members 36 held in place by aplurality of transverse beams 38 that are secured to the plate members36 and side plates 22 to permit relative movement thereof.

Each transverse beam 38 is somewhat shorter than the normal width ofplates 32 and is secured to only one of plate members 36 as by weldingat 42, alternate beams being connected to adjacent plates 36 in themanner illustrated in FIGURE 1. Furthermore, one end of each beam 38 isconnected as at 44 to the innerface of one wall 22, the end of the beamconnected being that end which is remote from connection 42 that bondsbeam 38 to plate 36. A clearance space is provided between the adjacentedges of plates 36 and between the outer edges of plates 36 and theadjacent wall 22 topermit substantial relative movement of the plates 36in accordance with H, -J contraction and expansion of the envelope coreWithin the housing.

The ultimate strength of the strongback assembly is dependent upon thenature of the reinforcing plate members 36 and the characteristics andfrequency with which the transverse beams are disposed across plates 36.

A modified form of strongback arrangement is illustrated in FIGURE 2Where a series of transverse beams 52 are arranged in substantiallyabutting relationship to provide a composite beam extending completelyacross the space between side walls 22 for the support of end plate 32.Each beam 52 is substantially shorter than the normal width of plate 32and is bonded at one end to plate 22 While the opposite end thereof isspaced from its adjacent plate 22, however adjacent beams 52 are bondedto the opposite side plates to provide a continuous backing supportacross plate 32. Furthermore, each plate 36 lying adjacent the fixed endof beam 52 is also bonded to said beam to provide a projecting portionor cantilever 56 that extends over the adjacent relatively movable plate36. To provide additional support for the projecting portion 56 of eachbeam 52, blocks 58 are abutted lightly against the upper edge thereofand connected to the fixed end of adjacent transverse beam 52.

What we claim is:

1. In a plate type heat exchange apparatus adapted for high internalpressure and Wide temperature variation a housing, said housingenclosing said apparatus and comprising a pair of side walls includingextensions protruding beyond ends of the enclosed heat exchangeapparatus, end walls adjacent the ends of said heat exchange apparatusextending perpendicularly between the side walls, a pair of spacedreinforcing plates abutting each end Wall; and a plurality of transversebeams supporting the reinforcing plates, each beam being connected toone of said side wall extensions and one of said reinforcing plates topermit relative movement of the other reinforcing plate with respectthereto.

2. In a plate type heat exchange apparatus adapted for high internalpressure and wide temperature variation a housing, said housingenclosing said apparatus and comprising a pair of side walls includingside wall extensions protruding beyond ends of the enclosed heatexchange apparatus; end Walls adjacent the ends of said heat 92;-

change apparatus extending between the side walls; a pair of spacedreinforcing plates abutting each end wall maintained in position by aplurality of transverse beams, said transverse beams fixed at one end toa side wall extension and spaced at the distal end from the oppositeside wall extension to permit relative movement therebetween.

3. In a plate type heat exchange apparatus adapted for high internalpressure and wide temperature Variation a housing, said housingenclosing said apparatus and comprising a pair of side walls includingextensions therefor that protrude beyond the ends of the enclosed heatexchange apparatus; end walls adjacent the ends of the heat exchangeapparatus extending between the side walls; reinforcing plates abuttingeach end wall to restrain fluid pressures within said housing; andtransverse beams extending across the reinforcing plates from anabutting side wall extension into spaced relation with the oppositelydisposed side wall extension, said transverse beams being connected tothe abutting side wall extension and the reinforcing plate remotetherefrom.

4. In a plate type heat exchange apparatus adapted for high internalpressure and wide temperature variation a housing, said housingenclosing said apparatus and comprising a pair of side walls includingextensions therefor that protrude beyond the ends of the heat exchangeapparatus therebetween; end Walls adjacent the ends of the heat exchangeapparatus extending between the side walls; a pair of spaced reinforcingplates abutting each end Wall to impart an increased resistance tobending thereto; and transverse beams crossing adjacent reinforcingplates, said transverse beams being fixed at one end to a side wallextension and the adjacent reinforcing plate to provide a cantileverportion at the opposite end thereof overriding the spaced reinforcingplate.

5. In a plate type heat exchange apparatus adapted for high internalpressure and wide temperature variation a housing, said housingenclosing said apparatus and comprising a pair of side Walls for saidapparatus including extensions therefor that protrude beyond the ends ofthe heat exchange apparatus; end walls at the ends of said heat exchangeapparatus providing walls for fluid passageways therein; spacedreinforcing plates extending longitudinally of said end walls; andtransverse beams extending across said reinforcing plates tosimultaneously hold them in position and provide stiffening meanstherefor, alternate transverse beams projecting from opposite side wallextensions.

6. A housing enclosing a heat exchange apparatus as defined in claim 5wherein the transverse beams are arranged in abutting pairs.

7. A housing enclosing a heat exchange apparatus as defined in claim 6wherein the beams extend transversely a distance substantially less thanthe width of adjacent end Walls supported thereby.

References Cited in the file of this patent UNITED STATES PATENTS1,767,397 Ragland June 24, 1930 2,108,087 Thayer Feb. 15, 1938 2,413,360Maquire et al Dec. 31, 1946 2,505,790 Panthofer May 2, 1950 7 2,526,135Holmes et al Oct. 17, 1950 FOREIGN PATENTS 917,045 France Sept. 2, 1946

